The investigation of a destructive fire to find its cause is necessary in order to determine whether there should be any civil liability due to defective products or workmanship and to determine whether the fire was caused by arson.
Through education, training and experience many individuals are able to inspect a fire scene and, based on fire patterns and other evidence observed at the scene, form an expert opinion on the cause and origin of the fire.
However, electrical malfunctions pose particularly difficult problems for an investigator because the extrinsic evidence looks the same whether a short circuit caused or was caused by a fire. For example, a staple through a Romex cable, an overloaded circuit or poorly installed conductors can cause an overload or overcurrent in the wires and, over a long period of time result in a breakdown of the insulation. Eventually, the conductors may come into contact with each other and short circuit.
Similarly, however, a raging fire or a fire from a trash can, cooking stove or the like, may itself destroy the insulating and subsequently result in an electrically similar short circuit having the same appearance.
A short circuit caused in either manner is usually apparent from the presence of melt beads or melted sections along the copper or aluminum conductors. Until now, it has been difficult and usually is impossible to determine whether these short circuits were caused by or caused the fire. Where, in the past, other evidence strongly suggested that the short circuit did not cause the fire, it was still impossible for the expert investigator to rule out on the basis of a laboratory test or analysis, for example in court room testimony, the possibility that the short circuit had caused the fire.